ABSTRACT The support of this career development award will help Jacqueline M Kruser, MD MS become an independent physician-investigator with the training and experience necessary to improve communication and treatment decision making for patients with critical illness. Dr. Kruser will use this award to build on her existing foundation in health services and outcomes research to achieve two career development goals: (1) Develop expertise in the application of systems engineering principles and methods in healthcare, and (2) Gain knowledge and experience in the conduct of clinical trials of complex behavioral interventions. These skills will expand Dr. Kruser's research focus beyond individual-level interventions to address the complex, system-level factors that influence treatment decision making and end-of-life care for patients with life-threatening illness, specifically in chronic critical illness. Dr. Kruser will achieve these career objectives through a 5-year career development plan that involves structured didactics, patient-oriented experiential research, and intensive mentoring. Dr. Kruser's career development will be mentored by Jane L Holl MD MPH, a physician with experience in applying systems engineering methods in healthcare, with over 20 years of sustained extramural funding, and an outstanding record of mentorship. The co-mentors of this award are experts in clinical trials and outcomes research in critical care (Richard G Wunderink, MD), and end-of-life decision making and behavioral intervention development (Margaret Schwarze, MD MPP). Dr. Kruser's career development will be supported by the exceptional institutional environment of Northwestern University, including the (1) Dedicated resources from the Division of Pulmonary and Critical Care Medicine and Department of Medicine, (2) Strong research infrastructure of the interprofessional Center for Healthcare Studies (directed by Dr. Holl), and (3) Established, productive collaborations between the McCormick School of Engineering and the Feinberg School of Medicine. Nearly 400,000 people in the US develop chronic critical illness each year, and most older adults with this condition will not survive beyond one year. Studies suggest that many older adults with chronic critical illness who are near the end of life receive unwanted care that does not reflect their goals, values, or preferences, referred to as ?goal-discordant? care. Thus, the overall research objective of this award is to apply the tools of systems engineering to adapt an existing individual-level communication tool, ?Best Case/Worst Case,? to reduce goal-discordant care in older adults at risk for chronic critical illness. Specific Aim 1 will identify the most impactful ICU system failures in communication and treatment decision-making through a Failure Mode, Effects, and Criticality Analysis. Next, Specific Aim 2 will use user-centered design engineering and simulation testing to adapt ?Best Case/Worst Case? to the complex ICU system. Finally, Specific Aim 3 will test the feasibility and acceptability of the novel intervention through a two-site, pilot clinical trial.